London's Metropolitan Police on Thursday identified the man as Adel Yahya, 23. He was arrested on Tuesday at Gatwick Airport as he got off a flight from Addis Ababa, Ethiopia.
He was charged with conspiring with four other men - all of whom are awaiting trial over the plot to attack three underground trains and a double-decker bus - "to cause by an explosive substance, explosions of a nature likely to endanger life or cause serious injury to property".
Yahya, from the Tottenham area of north London, is scheduled to appear at Bow Street Magistrates' Court on Friday.
A total of 16 people have now been charged in connection with the attempted attacks, which did not kill anyone as the bombs failed to detonate.
But the news shook Britain's capital two weeks after near identical suicide bombings killed 52 commuters on 7 July.
Five men are accused of plotting to murder passengers on London's transit system on 21 July and face trial in September.
Muktar Said Ibrahim, 27, Ramzi Mohamed, 23, Yassin Omar, 24, and Hussein Osman, 27, are accused of trying to bomb three underground trains and a bus. The fifth suspect, Manfo Kwaku Asiedu, 32, was arrested after a backpack of explosives was found in a raid. All face charges of conspiracy to murder.
Yahya is accused of conspiring with Osman, Ibrahim, Asiedu and Omar.
A further 10 people have been charged in connection with the attempted attacks - for failing to disclose information about the suspects and helping them evade arrest.